Patented June 14, 1938 2,120,485 UNITED STATES PATENT OFFICE 2,20,485 ORE FILOTATION Julius Bruce Clemmer and Robert Gibson O'Meara, Roila, Mo, assignors of one-fourth to Semmes and Semines, Washington, D. C., a firm composed of Harry H. Semmes and S. Warwick Keegin No Drawing. Application December 29, 1933, Seria No. 04598 10 (Caimas. (C. 209-6) This invention relates to the beneficiation of used for chemicals, they have a relatively Small ores, and more particularly has reference to the market. . flotation of tungsten. It will be seen, however, Thus it is apparent that a process such as flo that the invention embraces the flotation of min tation, which would successfully recover the fine erals other than tungsten from a gangue com now wasted and enable high grade con posed principally of calcite or other carbonate centrates to be produced from the more difficult . ores, would be of value in the concentration of The principal tungsten ores - Scheelite tungsten ores. Flotation would Serve as a use (CaO.WO3), ferberite (FeC.WO3), ful adjunct to gravity concentration processes O (Fe,MnO.WO3), and hubnerite (MnO.WO3)-are by making the milling circuit more flexible and O usually complex and contain a variety of aSSo permitting a higher recovery of an improved ciated minerals. The most common gangues are grade concentrate. By providing a Suitable flo quartz, feldspar, garnet, mica, Sulphides, ar tation process, the impurities could be more thor senides, carbonates such as calcite, ankerite, etc., oughly rejected and it would be feasible to mill and phosphates such as apatite. Particularly to ores which it is now considered impossible to 5 be noted in this connection is the fact that the treat. contact-metamorphic scheelite ores, which are While attempts have heretofore been made to the most important, usually contain a large float tungsten, no process has yet been devised amount of calcite or other carbonate minerals. whereby a high grade and merchantable concen Heretofore, tungsten ores have been beneficiat trate can be obtained. The difficulties in the 20 ed by hand-picking and gravity concentration past have resided, not so much in the inability processes, such as jigging and tabling. In order to float the tungsten, as in effecting a separation to achieve any semblance of success by gravity between the minerals and the various gangues concentration processes, however, there are two with which they are found. . conditions necessary. In the first place, there As stated above, our invention also comprises must be a pronounced difference between the the flotation of various minerals (particularly specific gravity of the mineral and the specific fluorspar, barite and scheelite) from calcite and gravity of the gangue, and in the second place, other calcareous minerals. The separation of the mineral and the gangue cannot be too finely these minerals by flotation methods has hereto 30 interlocked, but must be susceptible of separa fore been considered practically impossible. If tion by relatively coarse crushing. In the ab it be a fact that flotation by a fatty acid or de 30 sence of these two conditions, the concentrates rivative thereof depends upon the formation of are low grade and must be retreated by expen a relatively insoluble soap at the mineral sur sive chemical or pyrometallurgical processes in face, then, on account of the common order to produce marketable products. How ion, fluorspar, scheelite and calcite should act ever, even when the two conditions are present, the same in flotation, and barite should be simi 35 the concentrates, while of marketable: grade, lar in its flotative properties. This idea is Sup nevertheless account for a low recovery of the ported by the results obtained by many investiga tungsten. Furthermore, no satisfactory method tors working on a variety of ores. Separation by 40 for handling the fines has heretofore been avail flotation has been attempted by controlling the 40 . able. reactivity of the collector so that reaction pro At the present time, only the high grade and ceeds with only one mineral; these attempts have less complex ores are worked, and even in such case there are tailing dumps which contain large been made by controlling the pH and also by quantities of recoverable tungsten, provided a using various fatty acids of relatively short hy 45 suitable method of beneficiation can be devised. drocarbon chains. However, all previous at 45 The market requirements for tungsten ore are tempts to separate these minerals from calcite relatively rigid. Concentrates are sold by the or other by flotation, have short ton unit of contained tungstic Oxide (WO3) failed. 50 and the base is usually taken at 60%. Higher To overcome the above mentioned difficulties grade concentrates bring a correspondingly high is one of the objects of our invention. er price, and often a premium is given for ex Another object of our invention is to devise ceptionally pure material. Concentrates of lower a process, or processes, for the flotation of tung grade than 60% are difficult to sell and usually sten. 55 a penalty of several dollars a unit is imposed. Yet another object of our invention is to de 55 In addition to the required tungsten content, a vise a flotation process for tungsten ores in which concentrate for the ferrotungstic market must the concentrate is relatively free from impurities, not contain more than 0.05% of copper, bismuth, and is of a high and merchantable grade. antimony, tin, arsenic, sulphur, or phosphorus. Still another object of our invention is to de 60 Although some of the impure concentrates are vise a process for the flotation of certain minerals 2 2,120,485 from a gangue in which calcite, or other car Suffices, merely enough to make the pulp neutral bonate mineral, is an important constituent. or slightly acid. In no case should the acid be To accomplish the above, and other important added in an amount sufficient to dissolve the objects, as will be hereinafter observed, our in gangle. vention, in general, comprises the means and A fatty acid or derivative, or both, may be used 5 . steps herein recited, it being distinctly under as the collector, and, as in certain other instances stood, however, that various changes, and modi herein, a frother is not necessary under some fications, may be made therein without depart circumstances. A small amount of a soluble sili ing from the spirit of our invention or exceeding cate may be used to depress the quartz. The sili 10 the scope of the appended claims. cate may sometimes be omitted, however. The 10 The results herein set forth were obtained Only acid may be used either in the rougher or the after lengthy and numerous experiments, and cleaner, or both, but we have found that a slight the specific data submitted herewith is illus ly higher recovery of tungsten results when it is trative of the success we eventually obtained. used in only the cleaner. In a typical test on the Nevada Scheelite ore 16 Scheelite ore having a gangue composed of quartz and apatite, The first tungsten flotation tests made by uS and the heads assaying 3.16% WO3 and 0.04.0% were on a Scheelite ore from Nevada, in which P, a high grade Concentrate was produced assay the gangue was predominantly quartz with a ing 77.06% WO3, .036% P. and .03%, S. This con small amount of apatite. The early tests indi centrate accounted for 87.6% of the total WO3 20 cated that the scheelite was more floatable than and only 3.3% of the total P. A mechanically the quartz, and we found that the use of a fatty agitated flotation machine of standard design acid or a fatty acid soap, alone or together with was used, and the heads were ground to 150 a frother, and an alkaline reagent, gave a satis mesh. factory separation of scheelite. Any of the well The reagents used, and their respective 25 known fatty acids or fatty acid soaps may be amounts, were as follows: used, and the frother may be of conventional character, Such as pine oil, cresylic acid, the al Cleaners cohols, or any of the moderately soluble hetero Rougher polar Organic compounds which lower the sur a 30 face tension of water. Caustic SOda, soda ash or Sodium silicate may be used as the alkaline re Sodium silicate------Oleic acid------agent. Sodium oleate In One typical test, Such an ore, assaying 2.38% Formic acid tungstic Oxide, gave a Concentrate of 62.72% WO3, which constituted 89.7% of the total WO3 content It will be observed that the concentrates pro of the heads. The rougher concentrate was duced by this process were of a high grade and cleaned twice to give the final concentrate, and that the phosphorus and sulphur contents are in commercial operation the middlings, which well within the limits prescribed by the industry. 40 to assayed 1.03% WO3, would be returned to the We found that the rougher concentrates cleaned flotation circuit, and the mineral would be recov well. ered without a serious sacrifice in the grade of In neither of the preceding experiments did the the final product. ore contain any sulphide minerals. In view of The ore was ground to -100 mesh. As in the the fact that the flotation reagents employed for is d's case of all the tests reported herein (with one sulphides sometimes have a deleterious effect on exception, which will be referred to), the pulp the subsequent flotation of oxides, we conducted contained 17% solids. Flotation was accom a series of experiments on a sample of Montana plished in a mechanically agitated machine of Scheelite ore, in which the Scheelite was asso standard design. The reagents used per ton of ciated with gold, arsenopyrite, mica and quartz, so 0 crude ore were as follows: This ore also contained 0.636% of phosphorus as apatite. Rougher Cleaner We first conditioned the ore and then proceeded to float the gold and arsenopyrite. Flotation of Pine oil------the sulphides was followed by flotation of the sis s Oleic acid------Sodium oleate--- scheelite in a rougher and three cleaning stages, Sodium carbonate.-- High grade tungsten concentrates which were low in phosphorus and arsenic, were obtained, while the arsenopyrite concentrates contained the gold While the above mentioned test showed a satis and only a small amount of tungsten. The re- 60 factory recovery of the tungsten in the concen sults of a typical test on this ore are as follows: trate, the phosphorus in the concentrate was 0.246%, considerably higher than the .05 limit

Percent of already mentioned. This indicates that the phos total WOS is phorus-bearing mineral, apatite, floats with the 65 scheelite and is not completely depressed by the

alkaline reagent. Sulphide concentrates--- a ------2.0 After numerous experiments, we found that a Scheelite concentrates--- 89, 8 Middlings------25 9. ------8 low-phosphorus tungsten concentrate could be ob Tailings.------Ss. - P ------1.4 To tained by the use of a small amount of acid in the Composite------100.0 3.64------100.0 70 rougher or cleaner. The acids that can be used Heads------to depress the apatite may be the inorganic acids, such as hydrochloric, nitric, Sulphuric or Sul This test indicates that selective flotation can phurous, and the short-chained organic acids be successfully applied to tungsten Ores. such as formic or acetic. A small amount of acid The ore was ground to 150 mesh and a me- is 2,120,485 3 chanically agitated flotation machine was used. erably in grade. For instance, one ore contained The ore was first conditioned by the use of Sul over 25% calcite and only 0.37% tungstic oxide, phuric and lactic acids. Potassium amyl Xan whereas another contained only a trace of calcite thate and hardwood creosote were employed for and over 30% tungstic oxide. At the outset, it the flotation of the sulphides. We believe that should be stated that the amount of reagents has under most conditions, other conventional Sul to be varied to meet the need of the ore, and that . phide flotation reagents might be substituted, Ordinarily the proper amounts can only be de- . An additional amount of lactic acid was added to termined by experimentation. As a general rule, the Sulphide rougher to depress the mica, and however, a greater amount of calcareous gangue allow a clean sulphide concentrate to be produced. requires a greater amount of the metal salt O After the flotation of the sulphides, the scheelite silicate referred to hereafter. was floated with oleic acid and Sodium oleate, Referring to one specific experiment, carried and a small amount of silicate was added to re out on a Nevada, contact-metamorphic scheelite tard the quartz. These rougher concentrates ore, the ore was ground to -65 mesh and was 5 were cleaned with sodium silicate to depress the floated in a mechanically agitated flotation ma 5 quartz and mica, and a final cleaner with formic chine. Inasmuch as this ore contained pyrite acid depressed the remaining mica, and apatite. and sphalerite, the sulphides were first sepa It will of course be appreciated that suitable sub rated by the use of potassium amyl Xanthate and stitutions may be made for the above mentioned aerofloat, although any of the other conventional reagents, as occasion may Warrant. The amounts Sulphide flotation reagents could be used. In of reagents were as follows: asmuch as it is necessary to thoroughly remove the Sulphides in order to produce a Subsequent Sulphide Scheelite tungsten concentrate sufficiently low in sulphur, a relatively large amount of reagent is required. We have found that the sulphides can be floated 25 Cond. Rougher Rougher Cl. i. Cl. 2 Cl. 3 in an acid, neutral or alkaline pulp, without im pairing the floatability of the tungsten. Sulphuric acid---- After removal of the sulphides, the remaining LacticKamylxanthate.------acid------. 12 ore is conditioned for a short time with a heavy 30 Hardwood creo Sote------metal Salt, such as copper Sulphate. We have 30 Oleic acid------Sodium oleate found that the salts of other metals, such as Sodium silicate.-- silver, mercury, copper, lead, zinc, or , Formic acid.---- which form relatively insoluble carbonates, can be employed. While in the specific test to which 35 we refer, copper sulphate was used, other salts of We have found that the arsenopyrite readily copper such as copper nitrate, or copper am floats in the acid circuit, and that the lactic acid monium hydroxide, are as effective. We have re is especially effective in depressing mica, both in ferred to introducing the metal salt in the con the Sulphide flotation and in the flotation of ditioning stage, and prior to the flotation of the 40 scheelite. It is also effective in depressing apatite Scheelite, but we have found that it may also be but to a lesser degree than the inorganic or short added to the sulphide conditioner or during the chained organic acids. sulphide flotation, if the particular salt has no As will be seen from the above, the tungsten retarding effect on the sulphides. Of course, if concentrates in such a selective flotation process it has such a retarding effect on the Sulphides, 45 are of a high and marketable grade, and of a low phosphorus and arsenic content. it must be added after the sulphides have been 45 The three foregoing tests were made on floated. scheelite ores containing a siliceous gangue, and After proper conditioning, a soluble silicate, show that the Scheelite can be concentrated by such as sodium silicate, is added and thoroughly using a fatty acid or a derivative soap, or both. mixed in the pulp. After the silicate has been 50 sufficiently mixed, a fatty acid or its derivative 50 When there is no phosphorus present in the ore, soap may be added to float the Scheelite. The an alkaline circuit may be employed, but where metal salt-silicate served to effectively retard the phosphorus is present, an acid or non-alkaline calcite and apatite, and the scheelite rougher circuit is necessary in order to secure low concentrates obtained at this stage are of good 55 phosphorus concentrates. All of these ores were grade. 55 free of the calcareous minerals which occur The Scheelite rougher concentrates are cleaned abundantly in the contact-metamorphic ores. one or more times with a soluble silicate Or an Contact-metamorphoric scheelite ores acidic constituent to depress the small amounts of calcite and apatite which are floated in the 60 The presence of calcite or in scheelite roughing operation. While in the specific test 60 ores has heretofore been considered as preventing here set forth only silicate was employed, im the separation of Scheelite by flotation. The proved results have been obtained in other tests reagents that have previously been used have by using an acidic constituent such as acid di 65 not been effective in retarding or depressing the chromate, chromium nitrate, or any of the in calcite and inasmuch as calcite, Scheelite and organic or short-chained organic acids. In 65 apatite have about the same floatability, a sepa general, we have found that in tests in which the ration between them has been considered im proper amount of metal salt and soluble silicate possible. have been used in the rougher, silicate alone will 70 We have now devised a process by which readily clean the rougher concentrate. If the scheelite can be successfully concentrated from proper amount of these reagents have not been 70 ores containing a calcareous gangle, and We have used, however, then a final cleaning in a neutral been able to secure high grade concentrates, low dir slightly acid pulp is necessary to depress the in impurities. We have conducted our experi remaining calcareous material and apatite. 5 ments on a large number of ores varying consid In the specific test referred to above, the foll 5 2,120,485 lowing reagents were employed in the amounts centrate was obtained having a WO3 content of indicated: 59.54%, which accounted for 79.1% of the total WO3. Pounds per ton of crude ore This Ore was ground to -200 mesh, and the flotation was carried out in a mechanically agi 5 Reagents tated flotation machine. The ore was passed Sie 2. Rougher Cleaner i Cleaner2 through a rougher and three cleaners. The re agents used, and their amounts, were as follows: Kamylxanthate 10 A990at.------Cleaners 0 SodiumCuSO - silicate------Oleic acid------96------Sodium oleate------20 ------

As indicated above, the concentrates were of a Cresylic acid------Oleic acid.------15 high grade and were low in their phosphorus and Sodium oleate-- Sulphur contents. The results of this specific Sodium hydroxi Sodium silicate test were as follows: Sulphuric acid------Assay, percent 20 Wit. Percent of It will of course be appreciated that certain 20 Product pct. total WO substitutions may be made in the reagents listed WO P S in this application without materially affecting the results obtained. Sulphide concentrate.------6.0 2.74 ------7.0 With respect to the sulphuric acid used in the 25 Scheelite concentrate.-- 7.8-74.10 0, 0220,06 68.2 Middlings.------11.8 14.64 ------20.3 final two cleaners, we found that the ankerite and 25 Tailings--- 64.4 .60. ------4.5 siliceous gangue were effectively depressed. In Composite 100.0 8.49 ------100.0 other tests on ferberite ores, an acid was used in Heads------8,54 0.1375.27 ------the rougher as well as the three cleaners, and As will be seen, sodium silicate was the only we have found that acid dichromate is very ef 80 alkaline reagent employed, and it was used in fective in depressing the gangue and also the 30 the scheelite rougher. We have found as a result apatite. In one test, for instance, in which acid of other tests, however, that the use in the rougher dichromate was use at the rate of .05 lb. per ton or cleaner of caustic soda or soda ash in addition of crude ore in the rougher and 3 lb. per ton in to the silicate gives improved results. The re each of the three cleaning stages, a concentrate 35 covery is increased without a serious sacrifice in of 63.94% WO3 was recovered from a middling 35 the grade of concentrate. In a recent test, 86% . product from a mill treating a ferberite ore, which of the mineral was recovered in a concentrate as product had a composition of 31.16% WO3. The saying 70% tungstic oxide. concentrate accounted for 69.8% of the total WO3, We have also found that scheelite ores free of and had a phosphorus content of only .022% and 04.5% of sulphur. The other reagents used in 40 calcite, but containing considerable apatite may this test were oleic acid, sodium oleate and butyl also be effectively concentrated by using the metal alcohol. salt-silicate reagent combination in conjunction In certain ferberite ores, the mineral is par with the fatty acid. From Such an ore, tungsten ticularly sensitive to depression by acid, and in concentrates low in phosphorus can be produced. ' such cases we have found that the introduction of 45 45 by cleaning with a soluble silicate or an acidic a small amount of a metal salt renders the min reagent. f eral less sensitive but does not impair the efficacy Ferberite Ores of the gangue-depressing property of the acid. The flotation of ferberite has heretofore been Although not wishing to be bound by our explana considered impossible. Our investigations have tion of the theory, we believe that the metal Salt 50 shown that this was unwarranted, and, although functions to form a comparatively insoluble metal ferberite is not as floatable as scheelite, we have oleate coating around the particles, and thus rend devised a flotation process for the successful re ers the particle less sensitive to depression by the covery offerberite. , acid. Regardless of the theory, however, the net Most ferberite ores have a siliceous gangue result is a higher recovery of mineral in a con 55 SS with Only Small amounts of sulphides and apatite. centrate of slightly better grade. This metal While the ores which are liberated at coarse size salt-acid combination also serves to effectively de may be readily concentrated by gravity processes, press the apatite. It should be stated, however, ferberite is, generally speaking, brittle; and that a precise control of the acid will give com crushing produces rich fines which are difficult to parable results. recover by any process other than flotation. Con Ferberite seems to be best floated in an acid cir sequently, flotation serves as a useful adjunct to cuit, and, notwithstanding the fact that such ores gravity processes. Certain of the ferberite ores are relatively free of carbonates, any apatite contain an appreciable amount of hornstone com which may be present would be depressed by the posed of minute grains of ferberite disseminated slight acidity of the circuit. 85 - in a matrix of chalcedonic quartz. Inasmuch as During the course of the experimental work on such ores requirefine grinding for liberation, they the flotation offerberite Ore, some time was spent can be successfully treated Only by a process in the Boulder tungsten district of Colorado. adapted to handle material of this size, and we Flotation of ferberite under mill conditions was have found that flotation of these ores gives a attained. However, several difficulties had to be 70 70 good recovery of mineral in a concentrate of Overcome which are rarely encountered in labora marketable grade. tory work. The low temperature (34° F.) of the . In a typical test, on a ferberite-quartz ore con water available made flotation difficult. The taining an appreciable amount of ankerite, and ground ore was so dispersed that although the the heads of which assayed 10.24% WO, a con coare mineral was recovered by flotation in the 2,120,485 5 usual manner, the slime losses were too great. oleate at the rate of .10 lb. was used, and here too Further, the Consumption of fatty acid or soap the rougher concentrates were cleaned in the WaS greatly increased and flotation Was slow. first cleaner Without the addition of any reagents. Coagulation of the pulp by customary settling In the Second cleaner, butyl alcohol at the rate reagents such as line or Sulphuric acid further of .02 lb. per ton of crude ore was added, and .25 5 increased the Soap consumption and did not in lb. per ton of crude ore of acid dichromate was prove the flotation. It was found, however, that used to depress the apatite and quartz. the use of an alkaline reagent, as Soda ash, or a In this test, the ore was ground to pass 150 Salt such as calcium Sulphate, followed by a small mesh, and was floated in a mechanically agitated amount of an acid gave selective coagulation of flotation machine. The pulp, in this case, con 10 the mineral, whereas the fine gangue remained tained 34% solids. dispersed. The reverse order can also be used Compleac Ores acid followed by a base. The coagulated mineral was then readily floatable With the customary re From the above, it will be noted that certain agents and enabled a good separation to be ob Of the tungsten minerals are more floatable than 15 tained With low tailing losses. Emulsifying the others, and we have found that if they are ar fatty acid in the soap prior to flotation materially ranged in their order of increasing floatability, reduced the quantity of reagent necessary and Such order would be: ferberite, wolframite, hub nerite and Scheelite. We have found that Scheel gave normal flotation in spite of the cold tem ite can be Successfully separated from Wolfram 20 perature of the Water. ite, and, although this would not ordinarily be Wolframite done, it might be necessary to effect such a sep Wolframite, the manganese- tungstate, is aration in order to produce marketable grade slightly more susceptible to flotation than fer products from an ore that contains some other. berite, and the reagents used for ferberite act in additional mineral, such as fluorspar. In such 25 a similar fashion on Wolframite Ores. For in event, fluorspar and scheelite could be concen stance, on a Washington Wolframite ore which trated into one product and the wolframite into assayed 28.69% WO3, 0.05% P and 0.002% S, a another separate product. The separation of the concentrate was obtained of 70.92% WO3, 0.015% fluorspar could be effected in a retreatment of P and 0.01% S. This concentrate accounted for the fluorSpar-Scheelite product. In the absence 30. 89.4% of the total WO3. of such a procedure, and with the present state The ore was ground to -150 mesh, and floated of the art, separation would be almost impossible in a mechanically agitated flotation machine. if all three minerals were floated together. The reagents were as follows: Our experiments in this connection were con ducted on an ore from the Springvale mining dis 35 trict of Washington which assayed 1.48% tungs Cleaners tic oxide and 0.009% phosphorus. Wolframite Rougher - and Scheelite constituted the tungsten and were 2 3. associated with sulphides and gangue composed mainly of quartz and mica, and there were also. 40 ) Oleic acid------.96 ------Sodium oleate------. 40 ------present fluorspar, calcite, ankerite, apatite and Acid dichrolinate.------. 15 .. 5 . The complex nature of the ore and Butyl alcohol------.04 ---- the low tungsten content made testing difficult, but the results of Several tests Showed that the It will be observed from the above that the Ore could be satisfactorily concentrated by flo 5 rougher concentrates were cleaned once with no 45 reagents. We found that the wolframite floated tation. readily and that the dichromate effectively de In a typical test, the results were as follows: pressed the gangue. Assay, per cent Wgt. Pct. Of Hubnerite Product Pct. total WO 50 Due to the higher manganese content of hub WO P S

nerite, this ore is even more floatable than Wol Sulphide concentrate------1.9 2.7 framite, and the same reagents employed on fer Fluorspar concentrate----- 2.4 2.5 berite or wolframite may be used for the flota Scheelite concentrate------... 5 20.2 Wolframite concentrate. -- .9 4.5 55 5 tion of hubnerite. A typical test on an Arizona Composite mildlings 5.6 32.0 hubnerite ore which assayed 4.20% WO3 and Tailings------88.7 11 0.05% P resulted in the recovery of a concern Composite------0.0 100.0 trate assaying 71.56% WO3, .012% P and .043% S, accounting for 90.2% of the total WO3 con The ore was ground to -150 mesh, and floated 0 tent of the ore. in a mechanically agitated flotation machine. 60 This ore contained pyrite and chalco-pyrite, The procedure was, first, to fioat the sulphides, which were first floated by the use of 0.25 lb. of and then to float the fluorspar, Scheelite and potassium amyl xanthate per ton of crude ore calcareous materials in a second concentrate; and .14 lb. of butyl alcohol as a frother. Sodium and finally, a concentrate of the wolframite is 5 silicate at the rate of .65 lb. was used to prevent Secured. The Sulphides were floated with Xan 85 the tungsten from floating with the sulphides. thate and wood creosote, although other con We found that the use of these reagents did not ventional sulphide reagents might be employed, impair the subsequent floatability of the hub and a sufficient quantity of a soluble silicate is nerite. We also found that butyl alcohol is pref included to temporarily depress the scheelite and 0 erable as a frothing agent, inasmuch as it se Wolframite. 70 cured an equally good recovery of Sulphides but The fluorspar, scheelite and calcareous mate at the same time did not float as much tungsten rials were recovered in a concentrate that was as certain other frothers, such as pine oil. relatively free of wolframite, and a small amount . In the hubnerite rougher, oleic acid at the of oleic acid or oleate is all that is required for 5 rate of 0.40 lb. per ton of crude ore and sodium this step, if sufficient silicate is employed in 75 6 2,120,485 the Sulphide rougher. If sufficient silicate is heretofore the flotation of certain ores from cal not used in the sulphide rougher, it may be nec cite has been considered impossible. Specifically, essary to use it in the scheekite-fluorspar rough the prior art is replete with statements to the er. In any event, a silicate is used in the first effect that fluorspar and barite as Well as Scheelite cleaner in Order to depress any Wolframite, could not be successfully separated from Ores quartz or mica. The middling product was com containing calcite. bined - with the wolframite rougher concentrate It is true that on certain fluorspar ores, for in order to recover the wolframite. The fluor instance, which contain small amounts of calcite, spar-Scheelite concentrate was then recleaned it has been possible to reject Some of the calcite 10 with formic and hydrochloric acid in order to ef and produce fluorspar conicentrates relatively free 0. fectively depress the scheelite and yield a con of this constituent. Usually, what success has centrate of fluorspar that is fairly free of scheel been attained along this line has been due to the ite. The middlings are enriched in Scheelite and fact that the calcite was locked with the siliceous are of marketable grade with respect to the WO3 material and remained in the tailings or middling content. products. Furthermore, repeated cleaning of the 5 The tallings from the Scheelite-fluorspar rough rougher concentrates from an ore high in fluor er stage are subjected to a flotation treatment in spar but low in calcite does allow some of the which oleic acid and a small amount of oleate calcite to drop back into the middling product as are employed to float the wolframite. The con a result of a 'starving out process'. This simply centrate thus obtained is a medium grade and is means that the abundance of fluorspar Crowds contaminated with mica, quartz and some anker the calcite out of the froth. Even in such situ ite. The wolframite rougher concentrates are ations, however, much of the fluorspar remains cleaned by the use of manganese sulphate and in the middling products and consequently a low sulphuric acid, as well as hydrochloric and lactic recovery is obtained. acids. While, of course, not wishing to be bound When flourspar ores contain an appreciable by the exact amounts used, the following repre quantity of calcite there has heretofore been no sents quantities of reagents in the above men method by which concentrates low in calcite could tioned test: be obtained. We are well aware that a certain flotation process is claimed to effect a Successful separation of fluorspar from calcite. In this proc Sulphide Scheelite clean- Wolfram Cleaners ess the slime is removed either by a preliminary Reagents rougher rougher ite rougher de-sliming operation prior to flotation, or by frothing the pulp to remove the slime prior to Amylxanthate. floating the fluorspar. The sands are then floated Creosote.------in a Warming pulp using cresylic acid and oleic Sodium silicate.-- acid and the rougher concentrates are cleaned four times, In this cleaning the calcite drops back in the middlings which are removed from the flotation circuit because their recirculation prevents high grade fluorspar concentrates from sia acid being produced. It is to be noted that in this Lactic acid------prior process no actual depressant for calcite is used. As above stated, the final concentrates assayed We have experimented with a large variety of 45 well over 65% WO3, and were low in impurities. fluorspar Ores containing siliceous and calcareous 45 The results clearly show the feasibility of treating gangue and numerous reagents have been tested. this type of ore by flotation. We have found Several reagent combinations the results of all the foregoing tests show con which will effect a successful separation. , clusively that tungsten ores can be successfully For instance, we have found that sodium sili treated by flotation methods to yield high grade cate and an acidic reagent Such as acid dichro concentrates that are low in impurities. Fur mate are quite effective in depressing calcite. thermore, if sulphides are present in these Ores, Acids other than the dichromate may be used in they can be first floated by the customary re the flotation of these minerals. For instance, agents without affecting the subsequent flotation we have found that hydrochloric, nitric, sul of the tungsen. When the tungsten ores are free phuric and formic acids specifically give equally SS of calcite and apatite, good concentrates are re good results. In using this combination on a covered by merely using an alkaline depressant fluorspar calcite ore assaying 73.60% fluorspar, for the siliceous gangue. When they are free of 14.50% calcite and 12.25% quartz, which was calcite, but contain apatite, the apatite may be ground to -65 mesh, and floated in a mechan depressed by an alkaline reagent in the rougher ically agitated flotation machine, a concentrate and an acid in the cleaner, or an acid reagent was ootained assaying 97.71% fluorspar, 1.38% may be used in both the rougher and cleaner. calcite, and 0.89% quartz. This concentrate ac The combination of a metal Salt and soluble counted for 82.6% of the total fluorspar content silicate in the rougher, and an alkaline or acid of the ore. The reagents used were as follows: reagent in the cleaner, may be used on ores con taining calcite or other carbonates, in order to Pounds per ton of crude ore effectively depress such constituents. It will be appreciated that our invention may be applied to Reagents Cleaners 70 complex ores which have readily floatable gangue Rougher minerals, and also that Ores containing more than 2 3 4 5 one tungsten mineral are amenable to Our flota tion processes. Oleic acid------.96 ------Fluorspar Sodium silicate------. 40.4 i. 6 1.00 ------Reference has been made above to the fact that Acid dichromate.------i. 50 2.00 2,120,485 7 We found that a silicate followed by dichromate the calcite to give a high grade fluorspar con effectively depressed the calcite and Siliceous ma centrate. The exact amount of reagent for best terials, providing a minimum amount of collector results depends on the character of the ore...and is used in the rougher. Too much oleic acid, or must be determined by experimentation. Gen other fatty acid or derivative, produces rougher erally speaking, however, ores which contain con concentrates which are impossible to clean. It siderable calcite or which requirefine grinding will be observed in the above that this process for liberation require more metal salt and silicate produces fluorspar concentrates from ores con for a Separation. taining considerable calcite Without the necessity While not wishing to be limited by the theory 0 10 of a preliminary desliming or frothing operation, of the function of the metal Salt-silicate com and that the calcite is actually, depressed rather bination, we believe that the metal salt, used in than merely 'starved out'. conditioning, reacts With the carbonate mineral We have found that the Order in which the re to form a metal carbonate coating, and that the agents are introduced is immaterial, and, for in addition of silicate superimposes a coating of the 5 stance, dichromate may be used in the rougher metal silicate on the carbonate particle. Such 15. and silicate in the cleaners. As an example of coating may or may not be continuous, depend Such a process, we secured a concentrate assaying ing on the amount of reagent used and the time 98.18% CaF2, 1.06% CaCO3, and 0.56% SiO2, allowed for the reaction to proceed. The more Which accounted for 71.6% of the total fluorspar. complete the coating, the less tendency the par 20 2 The crude ore contained 69.93% fuorspar, 18.02% ticle has to float, and, in any event the silicate calcite and 11.02% quartz. The tailings con coated carbonate particle acts in flotation as a tained less fluorspar than in the test where sili true . Inasmuch as the fluorspar cate was used in the rougher. The rougher con does not take On the silicate coating, it is floated centrate was cleaned first with dichromate and by the fatty acid and the same thing is true with then with silicate. The calcite was depressed in respect to the scheelite above discussed and the 25 the middling and high grade fluorspar concen barite which Will be discussed later. If the cal trates were produced as above indicated. In this cite is insufficiently coated with the silicate, it will test the Ore was ground to -65 mesh and a me tend to float with the rougher concentrate, and in chanically agitated flotation machine was used, Such event a cleaning with additional silicate de 30 30 The ground ore was first conditioned with di presses such calcite or siliceous material that may chromate before adding the oleic acid in the have floated either for this reason or because an excess amount of collector was used. A final rougher. The amounts of reagents used were as cleaning with acid dichromate effectively de follows: presses the remaining calcite and siliceou Pounds perton of crude ore minerals, 35 The metal salt-silicate combination is effective Reagents Cleaners On Ores of any grade and the ores high in calcite Rougher are as amenable to treatment according to our 2 3 4 invention as ores containing only small amounts 40 of calcite. As an example, We conducted tests on 40 Acid dichromate------0.400. 6 ------a tailings product from a mill in the Kentucky Oleic acid------.80 ------Illinois fluorspar district which assayed 17.28% Sodium silicate------0.8 1.00 100 fluorspar, 73.61% calcite and 8.05% quartz. The clean mineral, of course, had been removed with We have found that another effective reagent Out difficulty in a gravity mill. Inasmuch as fine 45 45 combination consists in the use of copper sulfate, grinding was necessary to liberate the fiuorspar Sodium silicate, oleic acid and acid dichromate. from the gangue which was composed of siliceous In this process the pulp was conditioned with cop and calcareous minerals, concentration of such per sulphate for several minutes and then the sil liberated fluorspar by gravity methods was im icate was added. After a thorough mixing the possible. 50 50 oleic acid was introduced for floating the fluor This Kentucky-Illinois ore contained some sul Spar. The rougher concentrates were first phides which were first removed by the conven cleaned with silicate and then with dichromate. tional Sulphide flotation reagents, sodium, aero The amounts of reagents employed Were as float and aerofloat No. 25, and had no harmful follows: effect on the subsequent fluorspar flotation. A 55 55 fluorspar concentrate assaying 96.60% CaF2, Pounds perton of crude ore 2.84% CaCO3 and .01% SiO2 was obtained which represented 48.6% of the total fluorspar. The Reagents Condi Cleaners flotation tailings assayed 7.57% CaF2, which rep Old Rougher resented 19.1% of the total fluorspar in the ore. 60 2 3 The reagents employed, and the amounts, were as follows: Copper sulphate Sodium silicate---- Oleic acid.------Pounds per ton of crude ore 65 65 Reagents Cleaners In using this reagent combination on an ore Sulphide Rougher assaying 63.78% CaF2, 15.73% CaCO3, and rougher 19.96% SiO2 and which had been ground to -65 70 70 mesh, a concentrate assaying 98.25% CaF2, 0.86% Sodium aerofloat.------CaCO3 and 0.78% SiO2 was recovered, which ac Aerofloat No. 25. Copper sulphate: counted for 85.6% of the total fluorspar in the Ore. Sodium silicate. We have found that when the proper amount Oleic acid.----- of oleic acid and the metal salt-silicate combina 75 75 tion is used, the silicate alone effectively depresses S. 2,120,485 The pulp was conditioned with silicate before in Soap flotation, a mixture of free carbonates the oleic acid was added. As is apparent from appears to behave in a-manner that is inter the foregoing, good concentrates were obtained mediate between the reactions of its individual relatively free of Sulphides, calcite and siliceous constituents, and these constituents all float materials. simultaneously rather than in succession. Our Barite early experiments confirm the belief of the prior Our experiments have shown that barite can art. also be separated from calcite, in much the same Recent tests made by us, however, indicate way as fluorspar, the metal salt-silicate com that and the manganese dioxides 0. bination successfully retarding the calcite with may be separated from calcite by using the above 0. out affecting the barite. described metal salt-silicate combination, and a In a typical test, the ore was ground to pass careful control of the oleic acid. As a matter of 150 mesh for liberation of the mineral and fact, we believe that a successful separation of gangue, and the pulp was first conditioned with metal carbonates from calcite or the alkaline 5 copper sulphate. The reagents used were as earth carbonates generally is possible, and we follows: have no doubt that fluorspar, barite and Scheelite can be successfully floated from carbonates other than calcite. Pounds perton of crude ore It will be appreciated from all of the fore 20 going that We have devised a froth flotation proc Reagents Condi Cleaners OC ess which is adapted to recover valuable con tioner Rougher stituents of ores that have heretofore been con 2 3 sidered non-amenable to Satisfactory flotation. Our invention is economical and easy to carry 25 Copper Sulphate------1.00 ------Sodiurn silicate 0.8 0.4 0.25 out. The concentrates recovered are of a high Sodium oleate-- 2 grade, and the materials are effectively depressed. Oleic acid------The processes herein set forth should be appli Acid dichromate------cable to large bodies of ore that up to the present time have been considered unrecover 30 The concentrate recovered assayed 96.98% bar able, and also to large quantities of tailings. ite and 0.76% calcite, and accounted for 82.06% of It will be apparent to any person skilled in the the total barite in the feed. The bulk, 66.7%, of art that our invention is susceptible of a wide the calcite was depressed in the rougher. range of equivalencies, and that various modif Fluorspar-barite ores cations may be made in either the steps, the re agents, or the quantity of reagents, without de During the course of our experiments, we found parting from the Spirit of our inventive concept. that the barite was sensitive to dichromate, and In certain instances we have specifically listed that slight excesses of this reagent depressed the equivalent reagents, but it will be apparent in barite. Such was not the case With fluorspar, connection with practically every reagent, Our which was hardly affected by even large amounts range of equivalencies is not to be limited to such of acid dichromate in the cleaners. This indi expressed instances. For instance, where we cated that there was a possibility of Separating have used the term "fatty acid' in the specifica fluorspar from ores containing barite and cal tion or claims, it will be appreciated that this will cite, and in order to verify this, we conducted include not only fatty acids per se but also a series of experimentS. fatty acid derivatives, such as soaps, or both. We were able to effect such a separation, as is We claim: 45 evidenced by a test in which a fluorspar-barite 1. A method of floating minerals from calcite calcite ore, assaying 41.82% fluorspar, 19.19% comprising introducing into the mineral contain barite, and 33.80% calcite, gave a concentrate ing calcite, a collector having a fatty acid radical, of 82.56% fluorspar, 13.24% barite and 1.49% a frothing agent and a depressing agent for calcite, and which accounted for 84.1% of the calcite consisting of a heavy metal salt which total fluorspar and 29.4% of the total barite. forms a relatively insoluble carbonate and an The first middling, constituting 10% of the heads, alkaline silicate, agitating and aerating the mix assayed 23.56% fluorspar, 34.48% barite and ture, and then removing a concentrate relatively 37.52% calcite; and the Second and third mid free from calcite. dlings, aggregating 10.4% of the heads, assayed 2. A method of concentrating contact meta 11.21% fluorspar, 73.01% barite and 9.86% cal morphic scheelite ores comprising introducing cite. The reagents used were as follows: into the mineral containing calcite, a collector having a fatty acid radical, and a depressing agent for calcite consisting of a heavy metal Salt Pounds per ton of crude ore which forms a relatively insoluble carbonate and an alkaline silicate, agitating and aerating the Reagents Condi Cleaners OC mixture, and then removing a concentrate rela tioner Rougher tively free from calcite. 2 3 3. A method of floating minerals from calcite Copper sulphate------comprising introducing into the mineral con Sodium silicate taining calcite, a collector having a fatty acid Sodium oleate radical and a depressing agent for calcite con Oleic acid------sisting of an inorganic acid and an alkaline sili Acid dichromate------0.5 O cate, agitating and aerating the mixture, and then removing a concentrate relatively free from 70 Mineral carbonates generally calcite. As stated, it has heretofore been considered 4. A method of concentrating fluorspar that impossible to separate metal carbonates from cal also contains calcite comprising introducing into cite. Although the carbonates react differently the mineral containing calcite, a collector having T 2,120,485 9 a fatty acid radical and a depressing agent for 8. A method of concentrating Contact meta the gangue and calcite which consists of a solu morphic scheelite ores comprising introducing ble silicate and acid dichromate, agitating and into the mineral containing calcite, a condition aerating the mixture, and then removing a con ing agent of copper sulfate, then adding a soluble centrate relatively free from calcite. silicate to depress the calcite, introducing a col 5. A method of concentrating fluorspar ore lector having a fatty acid radical, agitating and containing calcareous and siliceous gangue com aerating the mixture and then removing the con prising introducing into the mineral containing centrate relatively free from Calcite. calcite acid dichromate as a conditioning agent, 9. A method of concentrating contact meta 0. then floating the fluorspar ore by a fatty acid morphic Scheelite ores comprising introducing 0 radical, depressing the gangue by a soluble sili into the mineral containing calcite a heavy metal cate, agitating and aerating the mixture and then salt which forms a relatively insoluble carbonate, removing a concentrate relatively free from cal then adding a soluble silicate and alkaline reagent Cite. to depress the calcite, introducing a collector hav 15 6. A method of concentrating a fluorspar Ore ing a fatty acid radical, agitating and aerating containing calcareous materials comprising intro the mixture, and then removing a concentrate 5 ducing into the mineral containing calcite a me relatively free from calcite. tallic salt conditioning agent, a collector having a 10. A method of concentrating contact meta fatty acid radical and a depressing agent Con morphic scheelite ores comprising introducing 20 sisting of acid dichromate and a soluble silicate, into the mineral containing calcite a heavy metal 20 agitating and aerating the mixture, and then salt which forms a relatively insoluble carbonate, removing a concentrate relatively free from cal then adding a soluble silicate to depress the cal cite. cite, introducing a collector having a fatty acid 7. A method of floating barite ores containing radical, agitating and aerating the mixture, and 25 calcite comprising introducing into the mineral subsequently cleaning the concentrate thus ob 25 containing calcite a metal sulfate, a soluble sili tained by a soluble silicate and an alkaline re cate, a collector having a fatty acid radical and a agent. depressing agent consisting of acid dichromate, agitating and aerating the mixture, and then JULIUS BRUCE CLEMMER. 30 removing a concentrate relatively free from cal ROBERT GIBSON O’MEARA. 30 cite.